There are like 6 different families of migraine
meds, so if one type stops working, there are more. My best advice is don't accept migraines as permanent, and keep fighting for solutions. If one thing doesn't work, move on and try different things.
The thing that's so crummy about migraines is that they affect every aspect of your life, and the most effective method to tackle them is from all directions. Eat well, take vitamins, try yoga or meditation, medication, etc.